Fade Particle to black

bonanza

Unregistered

Post: #1

Apr 2, 2008 — 10:46 AM

hi,
anyone know to how i can fade a particlecolor from red (for example) to black?
Fading works with all colors except black.
I have testet all blending-types, but nothing works.

here is my code

Code:

float r = p[i].startColor.r + (p[i].timeAlive / p[i].lifeTime) * (p[i].endColor.r - p[i].startColor.r);

float g = p[i].startColor.g + (p[i].timeAlive / p[i].lifeTime) * (p[i].endColor.g - p[i].startColor.g);

float b = p[i].startColor.b + (p[i].timeAlive / p[i].lifeTime) * (p[i].endColor.b - p[i].startColor.b);

glColor4f(r, g, b, 1.0);

OneSadCookie

Luminary

Posts: 5,125
Joined: 2002.04

Post: #2

Apr 2, 2008 — 11:16 AM

I don't see why that wouldn't work. What's the problem?

bonanza

Unregistered

Post: #3

Apr 2, 2008 — 11:28 AM

OneSadCookie Wrote:I don't see why that wouldn't work. What's the problem?

when fade to black, the particles fade out (transparent) but they should fade to black

Fenris

Oldtimer

Posts: 832
Joined: 2002.09

Post: #4

Apr 2, 2008 — 11:37 AM

Are you in GL_SRC_ALPHA, GL_ONE blend mode?

(Latest post: 16 Steps to Infinity)

bonanza

Unregistered

Post: #5

Apr 2, 2008 — 11:38 AM

Fenris Wrote:Are you in GL_SRC_ALPHA, GL_ONE blend mode?

I have testet all blending-combinations, nothing works

OneSadCookie

Luminary

Posts: 5,125
Joined: 2002.04

Post: #6

Apr 2, 2008 — 12:44 PM

Should be ONE, ONE_MINUS_SRC_ALPHA or SRC_ALPHA, ONE_MINUS_SRC_ALPHA depending on whether the underlying texture is premultiplied or not. Make sure the texture environment is set to MODULATE.

Nothing in what you've posted indicates why it would become transparent.

bonanza

Unregistered

Post: #7

Apr 2, 2008 — 09:57 PM

Thanks for reply.
Texture-Environment is setup correctly.
Here a screenshot of what i get
[Image: blend.jpg]

blendmodes:

Code:

glDepthMask(GL_FALSE);

glEnable(GL_BLEND);

glBindTexture(GL_TEXTURE_2D, texture);

//glBlendFunc(GL_SRC_ALPHA, GL_ONE);

//glBlendFunc(GL_ONE_MINUS_DST_COLOR, GL_ONE);

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

render...

Fenris

Oldtimer

Posts: 832
Joined: 2002.09

Post: #8

Apr 3, 2008 — 04:57 AM

It looks to me as if there's no alpha channel on the particle?

(Latest post: 16 Steps to Infinity)

bonanza

Unregistered

Post: #9

Apr 3, 2008 — 05:24 AM

I have testet textures with alpha-channel but no luck:
[Image: pic.jpg]

here is the effect what i want (fade from brown to black, and fade out)

[Image: test.jpg]

This is my textur:
$[Image: tex.jpg]$

This is my new code:

Code:

float r = _p[i].startColor.r * (1-(_p[i].age / _p[i].maxAge) ) + _p[i].endColor.r * (_p[i].age / _p[i].maxAge);

float g = _p[i].startColor.g * (1-(_p[i].age / _p[i].maxAge) ) + _p[i].endColor.g * (_p[i].age / _p[i].maxAge);

float b = _p[i].startColor.b * (1-(_p[i].age / _p[i].maxAge) ) + _p[i].endColor.b * (_p[i].age / _p[i].maxAge);            

float alpha = (_p[i].age / _p[i].maxAge);

glColor4f(r,g,b, 1- alpha);

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